Telephone system.



W. W. DEAN. v TELEPHONE SYSTEM. APPLICATION nun 110111, 1903.

Patented Dec. 15, 1908.

WILLIAM W. DEAN, OF CHICAGO, ILLlNOIS, ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPIXONE SYSTEM.

No. 906,513. sElggeeification of Le tors Patent. Patented Dec. 15, 190

Application filed November 11, 1903. Serial No 180,888.

To (ZZZ whom it may concern." I p rticula y pointed out in the appended Be it known that 1, WILLIAM 3T. Drum, c chihns, rc ercnce being had to the accomcitizen of the United States of Amer-ice, and pcnying droning i ming a part hereof in resident of Chicago, county of (look, and which the figure is a diagram of a telephone State of Illinois, have invented a new and system embodying my improvements.

useful Improvement in. Telephone Systems, in the figure, L and 1 indicate two subol WlUCl). the following is a specification. scribers lines extending in two limbs 2 and 3 lily invention relates to telephone systems from the respective substations Li and D to of the common battery type, in which two the central ollice (l, where they ilttcd, as batteries are provided at the central oflice for usual, with individual line signals S, preferesch conversation ably in the form of smell in cendcsccnt lamps, A common objection in common battery and with an answering jack J and a plurality telephone systems is that current from the of multiple jacks, J and J in any number, central battery must be present upon the according to the size of the switchboard upon telephone line when the subscriber is calling which they are placed.

the central cities to actuate his line signaling At the substations, the lines are provided relay or device and when ti o operator 2inwith the usual coll hell 4 and condenser :3 in swers the call the battery is disconnected :1 preferably permanent bridge of the line from the subscrib s line and again conconductors, and a transmitter 6 and receiver neoted therewith through the cord circuit to 7 in a. bridge that is nonnslly open at the furnish current over the fol-conversation. switch book 8. This uocsrctus intended This disconnection end reconnection of the merely to typify any usual or desired coni current source results in a violent noise in the men battery outfit subscrihers receiver, which is annoying even A line relay R and a cut-oil relay ll is prounder the most'i svorsble circumstances and *ided for each line at the central oliice, the in some cases it is practically impossible to latter being included in said line conductor 3 hold the receiver to the car while the operbetween the connection of the line relay l'lator is thus connecting with the line at the with the line and the said spring jacks or concentrsl ofiice. nection terminals of the line, said relay hov- My present invention relates to means for ing windings 9 and 10, the former being providing aso-cclled clicldess line, that is, logged to ground from the sleeve linc conducone in which practically no click or noise tor 3, while the other is connected between caused in me waiting subscribefls receiver the line conductor 2, and the spring 11 of the when the opsrot 1' answers the cell. out-oil reluy R the normal contact of said inv carrying out my invention 1 preferably spring being joined through the intermediaprovide each line withacut-otl relay, which in tion of a wire 12 with the common wire 13 the case of the calling subscribers line is actuconnected with the live pole of the central ated in one manner to render the correspondcommon battery B. The forward contact of ing line signal inoperative but to permit the said spring 11 is joined by a brunch conduc- '40 normal connection of the battery with the tor 14 with the common lead 15 connected line to remain undisturbed while when conwith a second central common battery B. nection is established with the called. line the The line signal is connected upon one side by *saidrelay of that line serves to both render a branch 16 with :1 second spring 17 of said the corres onding line signal inoperative and cut-oll relay R, the normal contact of which to sever t e connection with the normal betis joined by a wire 18 with said conductor 12,

tery and complete connection with the other. while the other terminal of said lamp is Other objects of the invention are to simunited throu h the medium of a wire 19 with plify the apparatus required and to provide the spring cl said line relc R, the forward an inexpensive and eilicient system,throughcontact 0t which spring is grounded. i 'hen out. the spring of the cut-off relay is zittn :d,

To the accomplishment of these objects it engages the small block of insulation 20 and such others may hereinafter sJpear, carried by the said spring 11, and is consethe invention consists in the parts on com quently insulated therefrom. binetions of parts hereinafter described and Each operator is provided with a plurality of cord circuits of the ty e sho'w'nin the drawing, each of which includes an answering plug P and a calling plug P having tip and sleeve contacts adapted to be re istered with the corresponding contacts oft e spring jacks of the lines when inserted therein. The tip contacts of the plugs are united through the flexible strands t and t and the interposed condenser 0, while their sleeve contacts are similarly joined by the strands s and s and the inter osed condenser 0 A pair of supervisory re ays r and r are bridged across the answering end of the cord circuit and together control the local circuit of the supervisory signal S associated with said answering plug, the latter relay beingadapted to .close said local circuit when energized and the former to open the same. An intermediate point of the bridge of these relays is connected b conductors 21 and 22 with the said battery ead 13, and a second pair of supervisory relays 1' and r is bridged across the calling end of the cordcircuit and is likewise connected with the said battery lead 13. These. relays together control the local circuit of the supervisory signal S The operators head tele hone 23, the secondai'y of her induction coi 24 and a suitable condenser c are adapted to be bridged across the calling end of the cord circuit inthe operation of any suitable listening key indicated by the springs 25, her transmitter 26 and the rimary of her induction coil being charged rom any suitable source of current. A test relay r of high resistance and hi li impedance and preferably common to al of the cord circuits at the operators position as indicated by the branching lines from the point 27, is adapted to be connected by normally open contacts 28 of the-listening key,

' conductor 29, the normal contact and extra spring 30 of the su ervisory relay 1 with the forward portion 0 said strand t The test relay is adapted when actuated to close a local circuit from said battery lead 18 through the conductor 31 including a tertiary winding of the operators induction coil. A suit ab e ringing generator 32 is adapted to be connected with the tip side of the cord circuit in the operation of the ringing key 33, the sleeve strand at the same. time being connected by conductor 34 with said battery lead 13'. 1

The su ervisory relays r and r are preferably ofhigh resistance, say 5000 ohms, while'the other su erv'isory relays r and r are preferably of a out 500 ohms resistance. The windings 9 and 10 of'the line rela B. are

- of about 100 ohms resistance, and t e cutenergized through the resistance of the 500 ohm supervisory relays. The other parts: may be of the usual'or desired dimensions.

In the operation of my invention, the sub scriber takes up his receiver, thereby completing a-path for current over conductors 1 3; and 12, spring 11, through the winding 10 of the line relay R, line conductor 2, thence to the substation devices and back to the central office over the line conductor 3 and,

ground. The current in this path is sulii-i cient to energize the line relay R, which closes the signal S from the battery lead 13, over conductors 12 and 13, conductor 16, through the lamp, conductor 19 and the closed contactsof the line relay R to ground. Upon observing the signal the operator inserts the answering plug'P of her cord circuit in the answering jack J of the line and depresses the listening key to connect her instrument with the cord circuit in use. The insertion of the plug P completes a path fort current over conductors 13, 22 and 21, through the supervisory relays T the sleeve strand 8 of the cord circuit, sleeve conductor of the telephone line, including the cut-off relay R thence through the winding 9 of the line relay R to ground. Owing to the high resistance of the supervisory relay in this path, the cut-off relay is actuated only sufficiently to separate its spring 17 from the conductor 18, thus retiring the line signal S, but insuflicient to separate said spring 11 from its normal contact, Thus the flow of current from the battery B over the path just described is uninterrupted by the con nection of the cord circult with the line. The supervisory relay R closes the local circuit oi the signal S and the supervisory relay 1* is energized by current from said conductor 21 over the tip strand t and the tip conductor 2 to the substation so that the said signal is prevented from glowing.

.Upon learning the order of the calling subscrib'e'r, the line is tested in the usual manner to determine its idle or busy condition. Normally the test rings of the lines are grounded through the winding 9 of the line relay and at the time that it is desired to make-the test the tip contact of the plug is likewise grounded through the spring 30 of the supervisory relay 1- conductor 29, contacts of the listening key, said key being operated at this time and through the test relay r Upon touching the tip of the plug to one of the test rings thereof, no flow of current takes place, and the operator lmows that the line is idle. 1-111;- case the line is busy, the said test rings are connected through the sleeve of the cord circui in use with the live pole of the battery B, and consequently when the grounded tip of the plug is brought into contact therewith a flow of current results and the same is actu' ated to close the local circuit through the tertiary Winding of the operators induction coil, thereby causing a click in'the operators receiver, and thus notiiying the operator that the line is busy.

Assuming that the line is idle, the calling plug is inserted and the ringing key operated to call the wanted subscriber. lnn'nediately upon the insertion of the plug, a path for 1 current is provided from the battery B ove. conductors i3, 22 and 2 l, through the supervisory relay 1". strand s ol' the cord circuit, conductor I} of the telephone line including the cut-oil relay 1, thence through the winding 9 of the line relay ll. Owing to the lower resistance of the supervisory relay 2'' that is now included in this circuit, the cutoli r4. .iy is lull actuated, thereby not only opening the circuit ol the line signal S to pre vent its operation and causing signals, but also to move the spring 11 of said relay lrom conmetiou with the conductor 12 into connection with the conductor lei leading to the live pole of the battery 3*. in the upsation of the ring ng key, the cut-oil relay is n'iaiutained actuated from the battery B through the medium of conductors l3 and 34-. and the sleeve spring 33 ot the ringing key. The ringing current is sent out over the tip side of the line with return over the sleeve side and through said conductors Pt and 13 and the battery B to ground.

After the subscriber has been called but before l'is response, the sleeve su jiervisory relay r is actuated over the path just tr ed and closes the local circuit of the supervisory signal S ass ciated \s'it-h the plug P, thereby lighting the said signal to indicate to the ooerator that the subscriber has not yet responded The operation of the said supervisor relay also disconnects the conductor :20 leading to the test relay and completes "he strand 3 of the cord circuit for conversation. Upon the response of the called Sill)- iber the supervisory relay rec-er suincient current l'roin "he battery B lio 5* ol the cord circuit to the same thereby c ion locactuah circuit of the supervisory signal S and retire the same,

During conver l on, the battery l3 lug currentto the telephone line 11 r operation of the transmitter at the substation A, While the battery B is feeding current to the line if for the operation oi the transmitter at the station Thus the potential. upon the calling line is practically constant during the operation of establishing the conncction so that the Waiting subscriber not disturbed by noise in the receiver; and the lines are supplied with current for conversation by thetwo batteries.

l in a telephone system, the conibinatioi'i with a plurality of telephone lines, ol a pair 1/ over th tip strand of sources of electricity at the central office, one of said sources being normally connected with the lines to iuri'iish current thereover when the subscribr-u' is calling the central oliice, a cut-off relay for each line, an operators cord circuit to establish connections with the lines for conversations, means whereby when the cord circuit is connected with a calling line the cut-oil relay of said line is actuated in one manner to render the line signal inoperative, the normal connection with said battery remaining undisturbed, and further means whereby when the con nection is established with the called line to complete the connection for eonYen-ation the cut-oil relay ol the called line is actuated in another manner to render the line signal incperath cand to disconnect the normal source and to connect he other source with the line, substantially as described.

in a telephone s stem, the combinatimi with a plurality of telephone lines, ol a pair of sources ol" current at the central oliice to furnish current 0 said lines for conyersiu t ion, one of said sources being normally connected. with the said lines to enable the subscribers to call the central Mike, at cut-otl relay for e ch line, a cord circuit to c connec ronswith the line lor conversr higl'l resistance device connected with the anrnreriug end ol the cord circuit and a low Lance device ccrrespon:hngly connected res s W1 th the (it end of the cord circuit, means .wil'fl l the cord circuit is connected w l a calling line the said high resistance device is connected in the circuit of the cut-oil relay of that line -whereby id cut-oil relay actuated t: such an extent only as to render the line signal inope'ratire, the normal o nection of said source ol current remaining undisturbed, and when the connection is estahli bed with :1 called line said low resistanc device is included in the, circuit of the cut-cu relay of that line to permit the latter to he comple ely operated to re lder the. signal inoporathre as well as to disconnect current source and to connect the other current source with the said line, substantially as d cribed 3. in a telephone system, the combination with a plurality of telephone lines, of a pair of sources of electricity at the central oliice with one olarhich said lines are normally connected to enable the subscribers to call the central ol'lice, an operators cord circuit, a cut-oil relay for each line, means associated with each end of the cord circuit to suitably control the operation of said cut-olirelays when connections are established with the lines, whereby when connection is estallished With the calling lines the normal connection oi" e first named source of current therewith remains undisturbed and when connection is established with the called .said batter the second attery connected therewith, sublines the said source is disconnected therefrom and the second source connected theretablished with t e lines whereby when connection is established with the calling lines the line signals are rendered inoperative but said normally connected battery remains in connection therewith and when connection is established with the called-for lines the line signals are rendered inoperative and the is disconnected therefrom and stantially as described.

5. In a telephone system, the combination with a plurality of telephone lines, of apair of sources of electricity at the central oflice with one of which said lines are 'normall connected to enable the subscribers to cal the central office, 'an operators cord circuit, a cut-ofl relay for each line, a high resistance supervisory relay associated with the answering end of the cord circuit and a low resistance supervisory relay associated with the calling end of the cord circuit, said supervisory relays being included circuit with the cutoff rela s when the cord circuit is connected with t e lines whereby the case of the calling lines the first named source of current remains connected therewith and in the case of the called lines said source is disconnected and the second source is con nected therewith, substantially'as described.

6.- In a telephone system, the combination with a plurality of telephone lines, of a cutoff relay for each line, said relays having two degrees of actuation, a pair'of sources at the central ofiice having terminals associated with the contactsof said cut-off relays, and means to differently actuate said relays whereby either of said sources may be con- .nected with the telephone lines, substantially as described. v.

7; In a telephone system, the combination with a telephoneline, of a line relay and a cut-off relay for the line, said cut-off relay having two degrees of actuation, the "circuit ,of the line relay being completed through one path when the cut-off relay is partially actuated and through another path when the but off relay is completely actuated and a separate source of current associated with each of said paths, substantially as described,

Signed by me at Chicago, county of Cook, I

State of Illinois, this seventh day of November 1903. k

WILLIAM W. DEAN.

Witnesses:

GAZELLE BEDER, v ROBERT Lnwrs AMES. 

